A NEW ARGOCOFFEOPSIS ( COFFEEAE , RUBIACEAE ) FROM SOUTHERN CAMEROON : ARGOCOFFEOPSIS SPATHULATA

In a recent phylogenetic investigation of tribe Coffeeae (Davis et al. 2007), based on four plastid regions and a morphological dataset, a clade containing the genera Argo­ coffeopsis Lebrun, Calycosiphonia Pierre ex Robbr. and an entity ‘Calycosiphonia cf.’ received strong bootstrap support (BP 99) and a high Bremer (decay) value (b = 9). Morphologically this clade is distinguished from other Coffeeae by the lack of a readily discernable seed coat (testa). Monophyly was identified for Calycosiphonia (BP 85; b = 3) and Argocoffeopsis (BP 81; b = 2) but Calycosiphonia cf., based on the sample (Sonké & Nguembou 3783, K, YA), was placed in an unresolved position at the base of the Argocoffeopsis–Calycosiphonia clade. Data from ITS sequences have not provided further clarification on this matter (A. Davis unpubl. data). These three taxa occur in tropical Africa, with Calycosiphonia cf. being restricted to Cameroon. Calycosiphonia cf. has all the key characteristics of Coffeeae (Bridson & Verdcourt 2003, Davis et al. 2007), including the presence of paired, axillary, sessile inflorescences, calyculi (calyx-like cupules at the base of the other inflorescence parts), coffee-like flowers (corolla tube narrow and more or less straight), ovules usually 1 or 2 per locule or up to 10, rarely c. 20 (1 per locule in Calycosiphonia cf.), and a distinctly bilobed stigma. Within the tribe this taxon is very distinct, owing to its large obovoid fruits and leaves with spathulate apices. It is clearly a new species, related to Argocoffeopsis or Calycosiphonia, but with no clear generic affinity. In general appearance Calycosiphonia cf. looks much more like Calycosiphonia than Argocoffeopsis, owing to its habit (a small, upright, single stemmed tree), with a rather


INTRODUCTION
In a recent phylogenetic investigation of tribe Coffeeae (Davis et al. 2007), based on four plastid regions and a morphological dataset, a clade containing the genera Argo coffeopsis Lebrun, Calycosiphonia Pierre ex Robbr.and an entity 'Calycosiphonia cf.' received strong bootstrap support (BP 99) and a high Bremer (decay) value (b = 9).Morphologically this clade is distinguished from other Coffeeae by the lack of a readily discernable seed coat (testa).Monophyly was identified for Calycosiphonia (BP 85; b = 3) and Argocoffeopsis (BP 81; b = 2) but Calycosiphonia cf., based on the sample (Sonké & Nguembou 3783,K,YA), was placed in an unresolved position at the base of the Argocoffeopsis-Calycosiphonia clade.Data from ITS sequences have not provided further clarification on this matter (A.Davis unpubl.data).These three taxa occur in tropical Africa, with Calycosiphonia cf.being restricted to Cameroon.
Calycosiphonia cf. has all the key characteristics of Coffeeae (Bridson & Verdcourt 2003, Davis et al. 2007), including the presence of paired, axillary, sessile inflorescences, calyculi (calyx-like cupules at the base of the other inflorescence parts), coffee-like flowers (corolla tube narrow and more or less straight), ovules usually 1 or 2 per locule or up to 10, rarely c. 20 (1 per locule in Calycosiphonia cf.), and a distinctly bilobed stigma.Within the tribe this taxon is very distinct, owing to its large obovoid fruits and leaves with spathulate apices.It is clearly a new species, related to Argocoffeopsis or Calycosiphonia, but with no clear generic affinity.
In general appearance Calycosiphonia cf.looks much more like Calycosiphonia than Argocoffeopsis, owing to its habit (a small, upright, single stemmed tree), with a rather 1) Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United Kingdom; e-mail: a.davis@kew.org.On basis of all the information given above we hereby take the opportunity to formally describe the entity known as Calycosiphonia cf.(Davis et al. 2007) as a species of Argocoffeopsis: A. spathulata.We see no logic in describing Calycosiphonia cf. in a new genus, as apart from the size and shape of its fruit, it shows no major morphological differences when compared with either Argocoffeopsis or Calycosiphonia.In a scenario that showed Calycosiphonia and Argocoffeopsis to be congeneric, the latter would have priority as it is the earliest published name (Lebrun 1941, Robbrecht 1981).

Argocoffeopsis spathulata
Distribution -Argocoffeopsis spathulata is restricted to the region of South Cameroon.
Habitat & Ecology -Argocoffeopsis spathulata occurs in closed-canopy evergreen forest with many epiphytes and a rich herb layer, classified by Letouzey (1985) as Biafran evergreen forests, rich in Caesalpiniaceae (Caesalpinioideae).This forest has a well-defined structure with a high degree of local endemism (e.g.Nguembou et al. 2006, Sonké et al. 2006).The area lies at 500-600 m above sea level.
Phenology -Flowering and fruiting in January, September, and November.